The field of art to which this invention pertains is desiccant devices.
Desiccant cartridges are used on containers, casings, reactors and the like which contain moisture sensitive products.
Desiccants cartridges can usually be exchanged from the outside of the container which is filled with the product to be protected from moisture. The cartridges are generally connected to the container by means of a sleeve or flange joint. The object of the desiccant in the desiccant cartridge is to protect the contents of the container from enclosed and penetrating atmospheric moisture.
Desiccant cartridges which are connected to containers, casings, reactors, and the like which contain moisture-sensitive products are generally divided into closed, open, or combined systems. The closed systems are not joined to the air which surrounds the container, whereas the open systems are joined to the ambient atmosphere. The combined systems are joined to the ambient atmosphere through pressure compensation valves which open when there is an under-or-over pressure in the container.
With the closed systems, there is often the problem that pressure compensation between the interior of the container and the surroundings is impossible, so that in some cases desiccant cartridges are provided with pressure compensation valves. The desiccant cartridges with the pressure compensation valves should be classed with the combined systems. The pressure compensation valves respond only when there is a desired under- or over-pressure in the interior of the container, joining to the surrounding air then being effected. In this case, however, air flows comparatively quickly-corresponding to the decrease in pressure--through the desiccant into the container or to the outside.
Open systems must be used for containers with moisture-sensitive products which are not designed for large pressure differences. However, these generally have the disadvantage that the desiccant is consumed comparatively quickly since an exchange of air with the surrounding air also takes place at all times.
These systems may nevertheless be necessary in various cases, namely, for example, when there is the additional object of neutralizing hydrogen sulfide or other acid/air mixtures and preventing their unfiltered admission into the atmosphere, by selecting a specific desiccant, such as aluminum gel or a molecular sieve.
It is precisely in cases of this type, however, that sufficient safety reserves of desiccant must at all times be kept ready in the cartridge so that, when there is an ejection of hydrogen sulfide as a result of inadequate adsorption capacity, no corresponding contamination of the environment results.